The invention relates to an apparatus for manufacturing short inorganic fibers such as glass wool, rock wool, ceramic wool which utilizes the centrifugal force of a rotation rotor and a gas stream.
An apparatus for manufacturing short inorganic fibers is generally provided with a rotating rotor and an delivery port which supplies a gas stream. The rotating rotor comprises a hollow cylindrical portion which defines a sidewall in which a number of apertures are formed therein to extend therethrough, a bottom which is integrally coupled to the lower end of the cylindrical portion, and a projecting portion which projects a melt radially inward from the upper end of the cylindrical portion around its full perimeter. A rotary shaft is connected to the bottom of the rotating rotor at its center and is adapted to be driven for rotation at a high speed.
A molten inorganic material is supplied into the rotating rotor and is subject to rotation therein so as to be externally thrown away through the apertures.
The delivery port for a gas stream is fixedly mounted adjacent to and above the cylindrical portion of the rotating rotor in an annular configuration so that the melt driven through the apertures in the rotating rotor under the influence of centrifugal force are blown away by a gas stream. One of problems which is experienced during the manufacture of short inorganic fibers such as glass wool, rock wool, ceramic wool with an apparatus as described relates to the erosion of the rotating rotor which occurs as a result of direct contact of the melt therewith, and oxidation caused by hot gas. The melt of a raw material which is supplied to the rotating rotor normally exhibits high temperatures above 1,000.degree. C. Accordingly, as the surface of the rotating rotor is eroded by contact of the melt therewith, the useful life of the rotating rotor is greatly reduced. Another problem relates to the apertures which is caused by continuous passing of the melt therethrough. Specifically, the internal diameter of these apertures tend to increase gradually as a result of the erosion.
To increase the useful life of the rotating, rotor, to stabilize the operation and to achieve a uniform quality of resulting short inorganic fibers, a normal practice is to employ an air cooling or a water cooling of the rotary shaft and the interior of the rotating rotor. However, even if the rotating rotor is subject to a cooling action, the useful life of the rotating rotor is normally on the order of 100 to 200 hours at most. Thus the rotating rotor must be frequently replaced, causing an increased cost and accompanying downtime of the entire apparatus for re-setting. Finally, there is a problem that the diameter of short inorganic fibers which are obtained as a product gradually increases with time.
In an arrangement of another type which is not provided with apertures, that is, where a cylindrical rotating rotor has its axis of rotation disposed horizontally and a molten inorganic material is supplied to the outer surface of the cylindrical portion of the rotating rotor by a free fall to convert it into fibers, the melt supplied is deposited on the cylindrical surface and undergoes a rotation together with the rotating rotor and is then blown away by a gas stream. Consequently, with time during which the rotating rotor is operatively used, the cylindrical surface of the rotating rotor which is disposed for contact with the melt becomes gradually eroded into an uneven configuration to cause an insufficient adhesion of the melt to the rotating rotor, thereby causing a more non-uniform distribution of diameters of fibers and an increased content of non-fiberized particles, thus degrading the fiber quality as a product.